Down syndrome (DS) is a genetic variation, a chromosomal abnormality, rather than a disease. To put it simply, a person with Down syndrome has got 47 chromosomes in total due to the presence of an extra copy of chromosome 21, while the total number of chromosomes in an ordinary human being is only 46.In our city of Samsun located in northern Turkey, the number of kids with Down syndrome is thought to be around 300.